System and method for rapidly shaking an implement of a machine

Abstract

A fluid system for use with a machine that employs an actuator, that provides for rapid shaking of an implement. The fluid system includes a source for providing fluid flow to the actuator and an operator input device for enabling an operator to control the movement of the implement by inputting a plurality of commands that specify movement of the implement. A controller is provided for monitoring the commands received from the operator input device and entering a mode for controlling the displacement of the source when the controller detects a pattern of commands that indicates an operator-request for rapid movement of the implement.

1. A fluid system for use with a machine that employs an actuator for moving an implement and which provides for rapid movement of the implement, the fluid system comprising:
 a tank for storing fluid; 
 a load sense pump fluidly connected to the tank for drawing fluid from the tank and providing fluid flow in the system; 
 a first valve fluidly connected between the pump and the actuator and between the tank and the actuator, the first valve configured to move between a plurality of open positions for directing fluid from the pump to the actuator and from the actuator to the tank, and a closed position that blocks fluid from flowing from the pump to the actuator and from the actuator to the tank; 
 a load sense line connected to the pump, wherein the pressure indicated by the load sense line represents the magnitude of a load acting on the implement; 
 a supply line fluidly connected between the pump and the first valve in which the rate of fluid flow is varied by the pump so as to maintain a constant pressure differential between the pressure in the supply line and the pressure indicated by the load sense line; 
 a second valve fluidly connected to the supply line for selectively permitting fluid to bypass the first valve and flow back to the tank; 
 an operator input device for enabling an operator to control the movement of the implement by inputting a plurality of commands that specify movement of the first valve between the positions for directing fluid; and 
 a controller configured to monitor the commands received from the operator input device and selectively activate a mode that provides for rapid movement of the implement when the controller detects rapid variations in the commands from the operator input device; 
 wherein the controller operating in the mode that provides for rapid movement of the implement activates the second valve based on a status of the first valve, the activation of the second valve including proportionately opening the second valve when the first valve moves to the closed position and proportionately closing the second valve when the first valve moves to an open position, wherein the activation of the second valve causes the pump to increase or maintain the rate of fluid flow in the supply line so as to maintain the constant pressure differential between the supply line and the load sense line. 
 
     
     
       2. A fluid system for use with a machine that employs an actuator for moving an implement and which provides for rapid movement of the implement, wherein the fluid system includes a source for providing fluid flow to the actuator through a supply line, and a main valve positioned in the supply line to control the fluid flow in the supply line, the fluid system comprising:
 an operator input device that controls the movement of the implement, the movement of the implement being controlled by moving the main valve between a plurality of open positions and a closed position in response to movements of the operator input device, the plurality of open positions being positions in which fluid flow is allowed between the source and the actuator, and the closed position being a position in which fluid flow is prevented between the source and the actuator; and 
 a controller configured to monitor the movements of the operator input device and selectively activate a mode that provides for rapid movement of the implement when the controller detects a pattern of operator input device movements that indicates an operator-request for rapid movement of the implement, wherein, in the mode that provides for rapid movement of the implement, the controller operates a bypass valve in concert with the main valve, the operation of the bypass valve including proportionately opening the bypass valve when the main valve moves to the closed position and proportionately closing the bypass valve when the main valve moves to an open position, the bypass valve being configured to selectively permit fluid in the supply line to bypass the main valve and flow to a tank. 
 
     
     
       3. The fluid system of  claim 2 , wherein the mode that provides for rapid movement of the implement is a destroke-reduction mode, the destroke-reduction mode being a mode that decreases a rate of displacement of the source. 
     
     
       4. The fluid system of  claim 3 , wherein the controller operating in the destroke-reduction mode proportionately opens the bypass valve when the main valve moves to the closed position. 
     
     
       5. The fluid system of  claim 2 , wherein the source is a load-sense pump. 
     
     
       6. The fluid system of  claim 5 , further comprising:
 a load sensing line connected to the load-sense pump, wherein pressure in the load sensing line represents the magnitude of a load acting on the implement and the load-sense pump varies the rate of fluid flow so as to maintain a constant pressure differential between the pressure in the supply line and the pressure indicated by the load sense line. 
 
     
     
       7. The fluid system of  claim 6 , wherein opening the bypass valve causes the load-sense pump to increase or maintain the rate of fluid flow in the supply line so as to maintain the constant pressure differential between the pressure in the supply line and the pressure in the load sensing line. 
     
     
       8. The fluid system of  claim 7 , wherein the mode that provides for rapid movement of the implement is a destroke-reduction mode, the destroke-reduction mode being a mode that decreases a rate of displacement of the load-sense pump. 
     
     
       9. The fluid system of  claim 8 , wherein the controller operating in the destroke-reduction mode further opens the bypass valve when the main valve moves closer to the closed position. 
     
     
       10. The fluid system of  claim 2 , wherein the mode that provides for rapid movement of the implement is a rapid-movement mode, the rapid-movement mode being a mode that decreases a displacement of the source. 
     
     
       11. The fluid system of  claim 10 , wherein the controller operating in the rapid-movement mode maintains the displacement of the source at 50% of a maximum displacement during a period when no commands are being received from the operator input device. 
     
     
       12. The fluid system of  claim 11 , wherein the controller operating in the rapid-movement mode maintains the displacement of the source at 50% of the maximum displacement by proportionally opening the bypass valve. 
     
     
       13. A method of controlling a fluid system of a machine, including an implement, to provide for rapid movement of the implement, the hydraulic system including a load-sense pump fluidly coupled to an actuator of the implement through a supply line, a load sense line that indicates a magnitude of load acting on the implement, a main valve positioned in the supply line to control fluid flow between the source and the actuator, a bypass valve configured to selectively permit fluid in the supply line to bypass the main valve and flow to a tank, an operator input device that controls the movement of the implement by moving the main valve between a plurality of open positions and a closed position in response to a movement of the operator input device, the plurality of open positions being positions in which fluid flow is allowed between the pump and the actuator and the closed position being a position in which fluid flow is prevented between the pump and the actuator, and a controller that operates the main valve to operate the implement based on the movements of the operator input device and initiates a mode that provides for rapid movement of the implement based on a pattern of movements of the operator input device, the method comprising:
 establishing an indicator characterized by a pattern of movements of the operator input device as a request for rapid movement of the implement; 
 monitoring the movements of the operator input device to detect for an occurrence of the indicator; 
 identifying the occurrence of the indicator; and 
 initiating a mode that provides for rapid movement of the implement at the occurrence of an indicator, wherein in the mode that provides for rapid movement of the implement, the bypass valve is proportionately opened when the main valve moves to the closed position and the bypass valve is proportionately closed when the main valve moves to an open position. 
 
     
     
       14. The method of  claim 13 , wherein the pattern of input commands that indicate the request for rapid movement of the implement is a rapid back-and-forth cycling of a joystick by an operator. 
     
     
       15. The method of  claim 13 , wherein the mode that provides for rapid movement of the implement is a destroke-reduction mode, the destroke-reduction mode being a mode that decreases a rate of displacement of the pump. 
     
     
       16. The method of  claim 15 , wherein the controller operating in the destroke-reduction mode decreases the rate of displacement of the pump by proportionally opening the bypass valve in response to an operator closing the main valve via the operator input device, wherein the opening bypass valve allows fluid flow from the supply line to the tank. 
     
     
       17. The method of  claim 13 , wherein the mode that provides for rapid movement of the implement is a rapid-movement mode, the rapid-movement mode being a mode that decreases a displacement of the pump. 
     
     
       18. The method of  claim 17 , wherein the controller operating in the rapid-movement mode maintains the displacement of the pump at 50% of a maximum displacement during a period when no commands are being received from the operator input device, wherein the controller maintains the displacement of the pump at 50% of the maximum displacement by proportionally opening the bypass valve for allowing fluid to flow back to a tank. 
     
     
       19. The fluid system of  claim 2 , wherein the bypass valve remains closed when the mode that provides for rapid movement of the implement is not activated. 
     
     
       20. The method of  claim 13 , wherein the bypass valve remains closed when the mode that provides for rapid movement of the implement is not initiated.